Good evening -- right. Tonight our nation is in debt to the people Boston and the people of Massachusetts. After a vicious attack on -- -- Bostonians responded with resolve and determination. They did their part as citizens and partners in this investigation. Boston Police. And state police and local police across the Commonwealth of Massachusetts was -- -- professionalism. And bravery over five long days and tonight because of -- determined efforts. We've closed an important chapter. In this tragedy. I've been briefed earlier this evening by FBI director smaller. After the attacks on Monday directed the full resources of federal government. To be made available to help state and local authorities in the investigation. And to increase security is needed. Over the past week. Close coordination among federal state and local officials. Sharing information. Moving swiftly there. Track down leads has been critical to this effort. They all worked as -- as a team and we are extremely grateful we owe a tremendous debt of gratitude to all our outstanding law enforcement professionals. These men and women get up every day they put on that uniform they risked their lives to keep us safe -- That's this week's show they don't always know what to expect -- -- Or -- those who were wounded in pursuit of the suspects and we pray for their full recovery. We also send our prayers to a call -- fans who grieve the loss of their son and brother -- He was born to be a police officer -- chief at MIT. He was just 46 years old. And as his family has said he does he died bravely. In the line of duty. Doing what he committed his life to -- serving and protecting others. So we're grateful to him. Obviously tonight there are still many unanswered questions. Among them why did it young men who grew up and studied here. As part of our communities. And our country. Resort to such violence. How -- they plan and carry out these attacks and that they receive any help. The families of those killed so sensible -- you deserve answers. The wounded some of whom now have to learn how to stand. Walk and live again deserve answers. And so I've instructed the FBI and the department of homeland security and our intelligence community. To continue to deport all the necessary resources to support the investigation. To collect intelligence. And to protect ourselves. We will determine what happens. We will investigate any associations that these terrorists may have had. And more continue to do whatever we have to do to keep our people -- One thing we do know is that whatever hateful agenda drove these men to such heinous acts. Will not cannot prevail. What are they thought they could ultimately achieve. Their party failed. They -- because the people of Boston refused to be intimidated. They fail because as Americans. We refuse to be terrorists. They fail because we will not waiver from the character. The compassion. And the values that define us as a country. Nor will we break the bonds that hold us together as Americans. That American spirit. Includes staying true to the unity and diversity that makes a strong. Like no other nation in the world. In this -- of instant reporting. Tweets and blogs. There's a temptation to latch on to a bit of information. Sometimes. To jump to conclusions. But when a tragedy like this happens. We have. Public safety. At risk and the stakes so high it's important that we do this right. That's why we have investigations. That's why. We relentlessly gather the facts. -- why we have courts. That's why. We take care not to rush to judgment. Not about motivations of these individuals. Certainly not about. Entire groups of people. After -- -- -- that makes America the greatest nation on earth but also one of things that makes Boston such a great city. Is that we welcome people from all around the world people very faith every ethnicity. Her record -- so as we continue to learn more about why and how this tragedy happen. Let's make sure that we sustain that spear. Tonight we think of all the wounded. Still struggling to recover. Certainly we -- of crystal Campbell. We think. -- -- We -- Little Marc -- Their lives reflected all the diversity and beauty of our country. And they were assuring a great American experience. Together. Finally let me say that. Even -- so much attention been focused on the tragic events in Boston. Understandably. We've also seen a tight knit community. In Texas. Devastated by a terrible explosion. And I want them to know that. They are not forgot. Our thoughts are prayers are with the people of west Texas where so many good people lost their lives. Some lost their homes. Many are injured. Many are still missing. Talk to Governor Perry and mayor Moscow. And I pledge that the people of west we'll have the resources that they need to recover and rebuild. I want everybody in Texas to know that we will follow through what those commitments. All always been tough week. But we've seen the character of our country wants more. And as president I'm confident that we have to -- and the resilience. And the spirit to overcome these challenges. And to go forward. As one nation under god indivisible. With liberty and justice -- Thank -- -- --

This transcript has been automatically generated and may not be 100% accurate.

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